Arrangement for driving the oscillator of a timepiece



Nov. 13, 1962 E. SCHONINGER 3,064,146

ARRANGEMENT FOR DRIVING THE OSCILLATOR OF A TIMEPIECE Filed Feb. 19, 1960 Fig.1 5 U gavoe AET Staes This invention is concerned with an arrangement for driving mechanical oscillators, especially balances in time pieces.

It is generally known that the drive impulses for maintaining the deflection stroke of balances or pendulums should be given as far as possible incident to the motion of the balance or pendulum through its zero position. It can also be demonstrated that the drive impulse may in some circumstances consist of a plurality of very short impulses for each half-oscillation provided that these impulses are efiected symmetrical to the zero position of the oscillator. In the case of electronically operated time pieces, great difiiculties are usually experienced in meeting the above noted requirement which is for reasons of regulation technique indispensible, and to satisfy at the same time all other technical requirements, such as obtaining a suitable control signal, proper form of the induction voltage, etc. Balance or pendulum motors known from contact-controlled time pieces can be directly used in transistor controlled time pieces only in few instances. Depending upon the control principle employed, they are in practice even found unsuitable.

The balance motors at present generally known employ as a rule one or more circular cylindrical permanent magnets for producing a constant electromagnetic field with respect to which a circular, triangular or elliptical coil can execute relative motions. With moving oscillator, a voltage is induced in the coil incident to passage through the electromagneticfield. In the case of time pieces containing transistors, this voltage can be utilized for the control of the drive impulses. However, the voltage signals delivered in known balance motors are in practice found to be more or less unsuitable for the intended operation.

The various objects and features of the invention will appear from the description which will be rendered below with reference to the accompanying drawing, wherein FIG. 1 is a diagram showing signals delivered in known structures;

FIG. 2 shows a structure for cording to FIG. 1;

FIG. 3 illustrates a structure according to the invention; and

FIG. 4 is a diagram showing the signals obtained in an arrangement according to FIG. 3.

The invention proceeds from recognition of the fact that, for example, the known triangular coil fastened upon a balance delivers in cooperation with two cylindrical permanent magnets a signal which is from the standpoint of regulation technique favorable but the shape of which is unsatisfactory. This will be realized upon examining FIG. 1 which represents the induced voltage U in dependence upon the time t, showing that the peaks 1 and 3 (or 4 and 6) are with respect to the peak 2 (or in a ratio of 1 to 2. Since the control mechanism for the balance motor is operatively actuated in response to the peaks 1, 3 and 5, depending upon the polarity of the induction voltage, the drive impulse will always occur under different electrical conditions. As has been Shown by investigations underlying the invention, this situation is very detrimental for the operating stability of such time pieces. Similar difliculties occur in connection with other producing the signals acatent arrangements in which the control signal lies non-symmetrical to the zero position of the oscillator. Accordingly these structures likewise fail.

In order to avoid these drawbacks, it has been proposed to construct an arrangement for the operation of mechanical oscillators, especially balances of time pieces, provided with at least one coil adapted to execute oscillations relative to electromagnetic fields generated preferably by permanent magnets, so that at least parts of the magnetically effective coil legs do not extend radially to the rotation axis of the mechanical oscillator, and wherein the elements (preferably permanent magnets) which generate the electromagnetic fields are so arranged that the voltage induced in the coil exhibits substantially the same peak values independent of the number of coil legs respectively permeated by the electromagnetic field in the course of the oscillation operation.

The present invention avoids the above explained dis-. advantages by arranging the elements for producing the electromagnetic fields so that the average distance of the field generating elements is greater or smaller than the average distance of the magnetically efi'ective coil parts, so that the voltage induced uring the oscillation operation exhibits the same or nearly the same peak values regardless of the number of elements generating the electromagnetic fields and coils or the operativeiy effective parts thereof. It is accordingly possible to produce by means of one coil with radially extending legs, a signal which is symmetrical with respect to the voltage maxima, provided that the magnets are not disposed in the same mutual spacing as the legs of the coil. It was until now with the use of permanent magnets of the customary kind, for ex? ample, with circular cylindrical shape and with the use of customary coils, impossible to obtain in the diagram according to FIG. 1 peaks 1, 3 and 5 of the same magnitude. For better understanding, there will be first explained the manner in which the signal according to FIG. 1 is produced with a normal two-leg flat coil cooperating with two circular cylindrical magnets.

If the coil Sp which is assumed to be rotatable about point 0 is moved from left to right, in the plane of the drawing, perpendicular to the fields of the magnets A and B, above the two magnets, the peak 1 Will be induced by the leg H upon sweeping over the magnet A (north pole). Shortly thereafter, the two legs H and H will stand aligned over the magnets A and B, thereby inducing the peak 2 which naturally is twice as great as the peak 1 since the magnetic flux through the coil is twice as great. The coil continues to move and the leg H passes over the magnet B (south pole), thereby inducing the peak 3.

When the coil moves in opposite direction, that is, in the plane of the drawing from right to left, the signal will be due to change of direction of opposite polarity, exhibiting the peaks 4, 5 and 6.

The present invention will now be explained with reference to FIG. 3.

The triangle-like flat coil Sp is fastened to a balance Ur which is in known manner adapted to execute rotary motions about point 0. Letters A and B indicate two transversely magnetized permanent magnets, the magnetic centers of gravity are symbolized by letters In and m. The points M and M of the two coil legs represent the centers of the electrically effective coil parts, that is, the electrical center of gravity of the coil legs. The width of the legs is indicated by s. Upon rotation of the balance by the amount of the angle a, about the rotation axis 0, a coil leg will be positioned approximately in alignment with one of the magnets A or B.

Upon assuming a deflection of the balance by more than (rotation to the left) from the position shown, there will occur in the coil during the successive oscillation period the following electrical actions. Upon return rotation (to the right) the magnet B will be passed over by the leg H Based upon Faradays induction law, a voltage is now induced into this leg corresponding to the peak I shown in the diagram FIG. 4, the maximum value of which is determined by the magnetic flux, number of turns of the coil and the angular velocity. Upon further rotation of the balance, H will leave the field of B and the leg H will after a brief interval cut the field lines extending from B. The arrangement of the coil-magnet is such that the leg H reaches the field of magnet A only when the number of field lines of the magnet B extending through H decreases. Therefore, leg H moves with respect to magnet B to alignment therewith. Immediately thereafter, leg H will enter the field of magnet A. When H is aligned with A, H has just left the field ofB. Shortly thereafter, leg H will also be in a position practically free of a magnetic field.

During the above described-operations, there will appear I at the terminals of the coil the voltage according to the central peak II with a magnitude approximately of that of the peak I. The duration of peak 11 is however twice as long since both magnets are in point of time affected successively by the coil. H will finally reach the field A and induce the peak III. Upon swinging back of the balance, the signal will have the same shape but opposite polarity, and there will be produced the'peaks IV, V and VI.

The arrangement of the magnets is such that the spacing of the magnetic centers of gravity m and m' is by about the width s of a coil leg greater than the spacing of the center points M and M of the legs H and H Anarrangement would also be feasible in which the spacing of the points m and m would be smaller by the amount s than the spacing M and M. The peak values of the induced voltage will then remain of equal magnitude, the structure of the coil will however be more unfavorable. The spacing W' could also exceed EITlF-l-s. A corresponding arrangement would however supply a signal expanded too much as to time, resulting in more unfavorable regulation conditions.

The signal receives for lflT-l-s -"rfifi the shape illustrated in FIG. 4, containing only peaks with the desired values of identical magnitude. The duration of the central peak II (and V) is twice the duration of peaks I and III (or IV and VI). This effect is desirable. As is known, a transistor amplifier employed for driving a balance re sponds operatively only to one polarity of the peaks and, therefore, in parts to the balance in accordance with the voltage course shown in FIG. 4, a drive impulse during one half oscillation and during the successive half period. Since the duration of the central peak is twice that of the preceding and succeeding peaks, the power delivered by thetransistor amplifier to the balance will be of the same magnitude during the two half oscillations.

In the described arrangement, the coil is in no position permeated by the total flux of all magnet elements. In

order to obtain in the coil as high a voltage as possible, relatively large preferably elongated or oval magnets are used so as to embrace substantially the entire electrically effective coil area.

Changes may be made within the scope and spirit of the appended claims which define what is believed to be new and desired to have protected by Letters Patent.

I claim:

1. In an electron transistor drive arrangement for the mechanical oscillator of an electrically operated time piece, the combination of an oscillatable drive balance, a coil operatively connected to a control transistor and oscillatable with said drive balance, a plurality of permanent magnets cooperably disposed with respect to said coil, relative movement of said coil with respect to the fields of saidrnagnets being operative to produce control and drive voltage impulses for maintaining oscillation of said drive balance, the average spacing between said permanent magnets being different than the average spacing between the magnetically eifective coil parts, the number of turns of i the coil'and the speed thereof which, with the relative spacing of said magnets and said coil parts, determines the magnitude of the produced impulse voltage, being such that said voltage is independent of the number of the coil legs which are'respectively traversed by flux so that the drive impulses exhibit substantially identical peak values of the induced voltage.

2. An arrangement according to claim 1, wherein the average spacing between said permanent magnets difiers by the width of a magnetically efiective part of said coil.

3. An' arrangement according to claim 2, wherein the average spacing between said permanent magnets is greater by an amount corresponding to the width of a magnetically eifective part of said coil.

.4, An arrangement according to claim 1, wherein said permanent magnets have an elongated cross-sectional shape, and the center points of said magnets lie upon the circumference of a circle extending about the axis of rotation of the drive balance. a I

5. An arrangement according to claim 4, wherein said coil is of generally triangular shape.

References Cited in the file of this patent V UNITED STATES PATENTS 2,143,074 Killman et al Jan. 10, 1939 2,888,797 Von Horn et a1 June 2, 1959 2,916,641 Held Dec. 8, 1959 2,924,797 Biemiller Q Feb. 9, 1960 2,936,572 .Biemiller et a1 May 17, 1960 Reese et'al Sept. 13, 1960 

